A knock sensor is a device for detecting knocks caused in an internal combustion engine. Conventionally, a knock sensor is fixed to a mounting portion of an internal combustion engine by means of a fixing member, such as a bolt, which extends through a through-hole formed in a support member that supports a piezoelectric element (i.e. a sensor element).
Japanese Patent Application Laid-open (kokai) No. 2004-85255 discloses a knock sensor having a support member made of a material, such as resin, having a relatively small Young's modulus to improve an output from the knock sensor.
A problem with this type of knock sensor is that the sensor is connected to an internal combustion engine with a top surface of a support member in contact with a fixing material (bolt), whereby the top surface of the support member is ground, i.e., abraded, by the fixing member (bolt) when connected to the internal combustion engine. As a result, the sensor performance of the knock sensor tended to vary. Specifically, when the support member was made of a soft material having a small Young's modulus, such as resin, the support member is more likely to be ground or abraded by the fixing member.
The present invention addresses the above-mentioned problem. An advantage of the invention is a knock sensor that is fixed to an internal combustion engine by means of extending the fixing member through a through-hole formed in the support member, and which is capable of protecting the support member from being ground by the fixing member.